We request support for continuation of a previously funded project lasting 14 months searching for environmental etiologies of adolescent sexuality and deviance. We have used high-quality data, a conceptual framework separating common and unique environmental influences, and analyses that link to both the data and the conceptual framework. Our general approach has involved constructing adolescent pairs that reflect different shared environments: siblings, classmates, and friends. The strongest results we obtained were for siblings, for whom we have shown influence and similarity for both sexuality and deviance. During the course of our previous work, we have noted some deficiencies in our data -- including lack of generality, small sample sizes, and limitations in the measures of deviance. In the proposed continuation of this research, we plan to link the work we have done on the ADSEX data with additional analyses of the National Longitudinal Survey of Youth (NLSY) dataset, a national probability sample of households that includes thousands of sibling pairs within the dataset. Measures of sexuality (weaker than those in the ADSEX data) and measures of deviance (stronger than those in the ADSEX data) are included in the NLSY data. In addition, we have developed contagious, "epidemic" models of the transmission of onset of sexuality, smoking, and drinking. Another goal is to explore their usefulness as explanations of the "spread" of social behaviors among adolescents. The long-range goal of this project is as in our original proposal: To develop a more complete understanding of the environmental influences on adolescent sexual and deviant behavior. Such understanding will help identify the appropriate arenas to which adolescent sexuality and adolescent pregnancy research and programs should be addressed.